Welcome to the fascinating world of ants! Today, we delve into one of the most intriguing species of the Northern Hemisphere: the highly organized harvester ants Messor barbarus. 

What does Messor barbarus look like?

These ants, varying in size from 3 to 14 mm, are easily recognizable by their black thorax and abdomen, with head colors ranging from dark red to light red. The distinctive red head helps differentiate them from other Messor ants. Covered in light hair, especially on the abdomen, these ants are a sight to behold.

Where do Messor barbarus come from? 

Messor barbarus is a Mediterranean species found in France, Spain, and North Africa. They thrive in rocky and sandy landscapes, dry fields, meadows, and orchards, preferring gentle slopes with sparse vegetation, sheltered from cold winds.

These ants hibernate from November to April, storing seeds in underground chambers to survive the winter. Their preference for dry, rocky soils is linked to their unique agricultural system. But before we explore their farming techniques, let’s understand why Messor barbarus ants exhibit such diverse shapes and sizes.

Polymorphism

Her Majesty, The queen

The queen’s lifespan is remarkable, living up to 20 years or more. During her lifetime, she lays millions of eggs, ensuring the colony’s growth and survival. As Messor barbarus is a monogynous species, there is only one queen per nest, making her role even more critical.

Minor workers

But the queen is not alone in her duties. The minor workers, the smallest ants in the colony, are always there to assist. These diligent workers, ranging from 3 to 8mm in size, are responsible for taking care of the brood. Watch how they move and cradle the eggs and larvae with such care and precision. Their small size allows them to navigate the intricate tunnels of the nest efficiently.

Media workers

Next, we have the media workers, who are intermediate in size, measuring between 8 to 12mm. These ants primarily work outside the nest, foraging for food and bringing it back to sustain the colony. Their size and strength make them well-suited for these tasks, bridging the gap between the smaller minors and the larger majors.

Major workers

Finally, we come to the major workers, the colony’s soldiers. These formidable ants can almost match the queen in size, with their large heads and powerful mandibles. Majors are the defenders of the nest, ready to attack any threat that comes their way. In the absence of danger, they patrol the area and assist other ants in cracking open the largest seeds, showcasing their strength and versatility.

A dynamic and adaptive colony

One of the most fascinating aspects of Messor barbarus is the ability of any ant to switch tasks based on the colony’s needs. This adaptability is triggered by a massive release of pheromones, which signal the ants to change their priorities. Whether it’s caring for the brood, foraging for food, or defending the nest, each ant plays a crucial role in the colony’s survival and success.

In the intricate and dynamic world of Messor barbarus, every ant, from the queen to the minors, media, and majors, contributes to the colony’s thriving ecosystem. Their cooperation and adaptability are essential.

Messor barbarus’ life cycle: From eggs to adults ants!

Stage 1: The Egg

The journey of a Messor barbarus ant begins as a tiny egg. These eggs are delicate and require the right conditions to develop properly. It takes about 10 to 14 days for an egg to transform into the next stage: the larva.

Stage 2: The Larva

Once the egg hatches, it becomes a larva. This stage lasts for 10 to 20 days. Unlike some other ant species, Messor barbarus larvae do not spin cocoons. Instead, they develop into what is known as a “naked pupa.” 

Stage 3: The Pupa

The pupa stage is where the most dramatic transformation occurs. Over the course of 10 to 25 days, the pupa gradually takes on the form of an adult ant. You might even see the pupa moving its antennas as it nears the end of this stage.

Stage 4: The Adult

Finally, the ant emerges as a fully developed adult. During the first days, the ant’s exoskeleton is still soft and clear, but it will harden and darken as it matures. The entire process, from egg to adult, takes approximately 30 to 50 days. This duration can vary depending on factors such as temperature, humidity, and the availability of food and proteins. It’s important to note that these numbers are theoretical averages, and individual ants may develop at slightly different rates.

Collecting seeds

From the 17th to the 19th century, scientists believed that Messor ants were detrimental to nature, hindering seed dispersal. However, modern research has revealed quite the opposite. Messor ants, particularly in desert environments, play a crucial role in seed dissemination, a phenomenon known as Myrmecochory. Studies have shown that plant biomass can increase twice as fast in the presence of these industrious ants. Additionally, research suggests that Messor barbarus has a direct impact on the distribution of cereal crops, making them valuable allies in sustainable farming practices.

Unlike some other species in the Messor genus that prefer solitary foraging, Messor barbarus ants work as a team. They create extensive pheromone trails up to 30 meters (100 feet) long, clearing the path of any vegetation or animal life. These ants often establish seed depots along the way, where seeds are temporarily stored before being transported to the nest by other ants. This teamwork is essential, especially during hot summer months when temperatures in regions like Spain and North Africa can exceed 30°C (86°F). The ants’ ability to adapt their foraging patterns, including shifting to nighttime activity when temperatures rise above 33°C (90°F), ensures the continuation of the good work.

How does a Messor barbarus ant select a seed?

First of all, a Messor barbarus ant always selects a seed that will fit in the nest. The bigger the nest, the larger the seeds they collect. A study conducted in the south of France suggests that these ants gather seeds ranging from 0.2 mg to 60 mg, choosing them from their favorite plants. Despite their preferences, they still collect seeds from 50% of the flora surrounding the nest. While adult Messor barbarus ants do not require proteins, the queen and larvae do. For certain species, proteins are essential, but they represent only 1% of the food collected by Messor barbarus ants. However, they can be fierce hunters when necessary, as evidenced by their swift capture of unsuspecting prey like slow worms or injured insects.

When a seed or its remnants are no longer useful, media or minor ants transport it to the waste deposit area. This area also serves as the final resting place for deceased ants

Inside the nest

A mature Messor barbarus nest counts around 90 000 individuals. The bigger part of the   colony works outdoors but what they do indoors is no less interesting. 

They extend the network of tunnels and chambers which is indispensable to the colony’s survival. Some of these chambers are dedicated to the brood, others are transformed into seed granaries. In both cases, the control of the temperature and the humidity rate is essential.

These ants store and check the seeds in the chamber, watching out that the seeds don’t start to ferment.

As you already know, ants don’t have any teeth in their mouths. They have what we commonly call  “mouth parts”. When it comes to eating they are similar to flies, transforming their food into a paste easier to swallow.

So, what was the solution that our clever barbarus ladies found?

The amylase present in their mouth glands facilitates the dissolution of the seeds, converting starch chains into glucose. This process results in a substance that is easier to cut, relocate, and share among the ants. When an ant requires nourishment, it simply sucks on this “bread” to extract the nutritive juice.

Additionally, there is considerable interest in whether Messor barbarus ants engage in trophallaxis, the process of food sharing from mouth to mouth. Observations conducted over a period of more than three hours did not reveal any instances of trophallaxis among these ants. However, it is theoretically possible, particularly when seeds are scarce, as the ants may resort to sugar-based liquids. In such cases, trophallaxis could become necessary. 

Notably, Messor barbarus ants exhibit a high frequency of mutual grooming. This behavior underscores the collective nature of their existence, extending even to their hygiene practices.

So…

Messor barbarus ants have chosen a different evolutionary path than other ants. While leaf cutter ants cultivate fungi and Formica rufa build domes made of twigs, Messor barbarus are harvester ants. Ongoing studies suggest that Messor nests could be significant reservoirs of myrmecophile diversity, hosting some of the most distinctive symbionts.

This diverse community of symbionts means that Messor barbarus not only contributes to the development of flora by dispersing seeds but also supports the fauna by providing a habitat for these insects. This intricate web of interactions highlights the ecological importance of Messor barbarus in maintaining biodiversity and ecosystem stability.